linux-4.4.1/dma_alloc_from_contiguous() の履歴(No.2)

• 履歴一覧
• 差分 を表示
• 現在との差分 を表示
• ソース を表示
• linux-4.4.1/dma_alloc_from_contiguous() へ行く。
  • 1 (2016-02-26 (金) 19:08:45)
  • 2 (2016-03-07 (月) 21:37:18)

参照元†

• linux-4.4.1/__alloc_from_contiguous()
• linux-4.4.1/__dma_alloc_coherent()(arm64)

説明†

• パス: 複数あり
  • CONFIG_DMA_CMA 有効: linux-4.4.1/drivers/base/dma-contiguous.c
  • CONFIG_DMA_CMA 無効: linux-4.4.1/include/linux/dma-contiguous.h
  • linux-4.4.1/CONFIG_DMA_CMA

• FIXME: これは何？
  • 説明

引数†

• struct device *dev
  • linux-4.4.1/device
• size_t count
• unsigned int align

返り値†

• struct page *
  • linux-4.4.1/page

参考†

実装†

CONFIG_DMA_CMA 有効: drivers/base/dma-contiguous.c†

/**
 * dma_alloc_from_contiguous() - allocate pages from contiguous area
 * @dev:   Pointer to device for which the allocation is performed.
 * @count: Requested number of pages.
 * @align: Requested alignment of pages (in PAGE_SIZE order).
 *
 * This function allocates memory buffer for specified device. It uses
 * device specific contiguous memory area if available or the default
 * global one. Requires architecture specific dev_get_cma_area() helper
 * function.
 */
struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
                                       unsigned int align)
{
        if (align > CONFIG_CMA_ALIGNMENT)
                align = CONFIG_CMA_ALIGNMENT;

• • linux-4.4.1/CONFIG_CMA_ALIGNMENT

        return cma_alloc(dev_get_cma_area(dev), count, align);

• • linux-4.4.1/cma_alloc()
  • linux-4.4.1/dev_get_cma_area()

}

CONFIG_DMA_CMA 無効: include/linux/dma-contiguous.h†

static inline
struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
                                       unsigned int order)
{
        return NULL;
}

• 常に失敗する。

コメント†